Automatic telephone system.



A. E. KEITH.

AUTOMATIC TELEPHONE SYSTEM. APPLTCATIONTZLED run 6. I908 1,237,208. Patented Aug. 14,- 1917.

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A; E. KEITH.- AUTOMATIC TELEPHONE SYSTEM.

YAPPIJCATIOAN man JuLY' 6, 190s.

Patented Aug. 14, 1917.

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APPLICATION FILED MY 6. I908.

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@UTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED jULY 6, 1908. 1,237,908. PatgntedAu 14,1917.

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.A. E. KEITH.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED JULY 6,1906.

Patented Aug. 14, 1917.

"UNITED STATES PATENT oFEIoE;

ALEXANDER E. KEITH, or I-iiINSDALE, ILLINOIS, .assIsuoze T Aorom'mc- ELno'rnIc oomrm, or omcnoo, ILLINOIS, A CORPORATION or ILLINOIS.-

' nu'rom'nc 'rntnrnoun sys'rum.

specification of Letters Patent.

Application filed m c, 1908. Serial No. 442,124. a

To all whom it may concern! Be it known that I, Ann mnnnn E.'KE1TH, a citizen of the United Sta, of'AIn and'resident of 'Hinsda le agecounty,

Illinois, have invented a useful Improvementin'Aut Systems, of which the follow s }.a"specification.

My invention relates to automaticor semiautomatic telephone exchange systems of that character in which the automatic switches have vertical motion to select groups or-divisions' ofthe exchange and.

rotary motion to connect with a, line in'theselected group or division, the, vertical mo.- tion of the switch being always under the direct control of the calling subscriber, or. an operator, but the rotary motion being antomatic if the switch is for ,the.;purpose of selectingidle trunks, .or undenithef control of the calling subscriber if suchfrotary mo- I tion is for the purpose of making the final or subscribers lines, dependingupon whether connection directly with the line of the called subscriber, the vertical-motion, howei'er, being in either case for the purpose of selecting a group of lines, either trunk-lines the switch is a selector oraconnector, and the rotary motion in either case being for the purpose of connecting with a line in the selected group, although for the broader.

' purposes of my invention, as will hereinafter more fully appear, all'of'the switches in the exchange need not. be characterized, by both the vertical and rotary motion, as my inventioncontemplates, in one res (act at least a novel form of connector switc for use in conjunctionwith other switches of any-suitable, known or approved charactena The principal object of m invention is, therefore, the"-prov1s1on 0 a connector switch having a capacity of at leasts'onethousand subscribersflines, and in which the wipers, although having both vert cal and rotary motion, are soarranged that each line wiper takescare ofmore than one hundred lines, preferably five hundred lines, thus-obviating thenecessity ofproviding a .separate wip'erfor each one hundred lines, notwithstanding thefactthat said wipers have both vertical andxrotary' motion whenever they are used to extend connection to a i called subscribers line I also provide, .as will" hereinafter more fully appear, a trunking arrangement where- Patented Aug.

'by each subscriber doesnot have 'acces to j all of the groups of connectors and, therefore, doesnot have access to all of the simply to' as many groups 'of connectors cent. trunking: this means that each subscriber has access to as many connectors as there are hundreds of subscribers to the 'ex'changethat is to say, if there are .ten

thousand subscribers to the exchange, then difierent connectors of the exchange,. but

H r as there -.arethousands, and .with ten per' each subscriber will. have access to ten groups and-hence to one hundred connectors, therebeing one thousand connectors In all, whereby the maximum number of subscribers calling at any one time are given proper 4 trunking and connecting facilities.

It is also an object to provide certain novel I details and combinations tending to increase the. general efiiciency and se'rvice'ability of an automatic one thousand line connector switch and system therefor of this particu-' lar character.

'- To the foregoing and'other useful ends, I

my invention consists in: mattershereinafter set forth and claimed.

In the accompanving drawings Figure 1,

is a diagram of an automatic telephone sys-- tem equipped with my improvediconnec-tor switch A'. At t.-therelis represented a firsts'elector switch the" line of which leads to substation D.

Fig. 2 shows diagrammaticallya first-' selector switch-C allotted to-the subscribersstation D Figs. 3, -l and 5' show details of the operwtive mechanismof the connector switch shaft.

Figs. cand T are, respectively, a side ele-. I

vation andplan view of the wiper and hun:

dreds selecting mechanism of the connector switch.

a section or portion of the trunking arrange- Fig, 8-"is a cross-section of :the wiperson BEST AVAILABLE COP ment'of a ten thousand systemv embodying p the principles'of my invention.

V Fig. 14 is a diagrammatic illustration of a portion of the trunking arrangement of a" 100,000 system embodying the principles of, my invention. i

In Fig.1 a central battery B, for both talking and operating purposes,'is shown having its positive terminal preferably grounded at G. At E is shown a ringer generator, and at F is represented a busy-signaling machine. i

The substations D and D 'are of thegeneral type disclosed in United States Letters Patent No. 866,639, granted September 24,

1907, to E. D. Fales, and are adapted for V common battery work. Substation D comprises a receiver 2, switch-hook 3, induc-' tion coil 4 which consists of the primary winding 5 and secondary winding 6, transmitter 7 ringer'S and condenser 9. In ad- -.dition to the above-mentioned parts there is' 15, 16 and 17 and is pivotally secured to the.

frame (not shown) of the calling device.

The cam arm15 controls the so-called locking cam 18 which in turn controls the co- .operating ground Springs 19 and 20. hen

these ground springs engage, ground is thereby provided to the ground post 21 from paratus broughtinto service the substation ground G. WVhen the switchmg the ringer 8 in's'eries with the condenser 9 across the line. The springs2-1 and 25 are then disengaged, and the primary circuit is interruptedl The signaling device, whereby.

a subscriber may signal another aftercon- .nection has been established, comprises a push-button spring 26 which normally engages the contact point 27; but when the button is pres ed the said spring leaves the contact point 27 and engages the contact point '18 which is connected to the substation ground G Means whereby a subscriber may release the central station switchingapcomprises the three springs 2 30 and 31. known as the release springs which are so controlled by the cam arm 17 that when the switch-hook descend thethree'release springs are brought into contact. thereby grounding both of the subscribers line conductors simultaneously. The first-selector switchcsC and C are of 4 i the type disclosed in United States Letters Patent No. 815.321. granted March 13, 1906,

5:; .to Keith, Erickson and Erickson. The Inc? chanical details of the first-selector switch "are, in general, well known, involving a switch shaft (not shown) which carries the line wipers 323ml 33 and the private wiper 3 1. The side switch is controlled by the private magnet 35, and when the side switch is in normal or first position the side switch wipers 36,37, 38 and 39 occupy the position shown by the dotted lines in Fig.1. In the second position the wipers engage the middle contact points, and when the side switch passes to third position the wipers 36, 37, 38 and 39 engage the contact points shown by full lines in Fig. 1. While the side switch is' in first and second position the calling subscriber controlsthe switch by means of the vertical and rotary line relays 40 and 11,-

which latter are connected to the battery lead through the springs of the bridge-cutofi relay 1'2. ll'hile the Side switch is in first position the calling subscriber controls the vertical magnet 13, which operates 'to give the switch sha ft a vertical motion. By means of the rotary line relay 11. an-d while the side switch is in first or second position, the

subscriber controls the private magnet 35 andytherefore, the side switch. YVhen the side switch isin secondposition the rotary magi'iet lt is energized. and the switch shaft that carries the wipers 32, 33 and 31 is operated in a rotary direction. ,T he vertical and rotary line relays, acting conjointly, provide the means by which the release magnet 15 is operated by the subscriberwhile the side switch is in first or second position. If

the side switch passes to third position, however,'s1nce the selector C is of'the trunk-release type the release magnet 45 is then con- 1 trolled through the connector A by way of book is down the cam arm 16 maintains the springs 22 and 23 in contact, thereby bridgthe privatewiper 34: and by means of the back-release relay The mechanical details of the selector and connector switches, as is well-known, are very much the same. The present connector switch is of the general type of connector switch disclosed in United States Letters Patent Nos. 815,176, granted March 13, 1906, to Keith, Erickson and Erickson, and 830,653 and 830,65'-l,'granted September 11, 1906, to A. H. Dyson, with the addition of the wiper-selecting mechanism shown in Tlie ver ical'line relay-53 directly controls Figs. 6 and 7. Furthermore, the connector 7 sofcar'ries the master wiper 80.

the vertical magnet 54, the shaft rotary magnet 55;,a11d also the wiper-selector 1'0- tary magnet 56. The rotary line relay 57 controls the private magnet 58 and the SWltClllIlg relay 59 Theprivate magnet 58, under certain conditions, controls in turn the vertlcal and rotary magnets 54 and 55, the release magnet 59, and also the side I switch wipers 60,61, 62 and 63.- The side switch, of course, has a normal or first positlon, a second positionand a third position. The release magnet 59. isalso controlled by -j the vertical and. rotary .line relays 53 and 57 conjointly. By the usefofthe condensers "'64 and 65theicircuit through the connector.

is divided into'two sections.-- The connector I 53, to control the ringer relay 70 by means ofwhich'the ringer generator E .is bridged across the terminals of the called line to signal the called subscriber.

is provided with adifi'erentially-wound re- GG-whichis composed. of the two'wind- Kings 67 andj68. -The function of thisrelay is to provide the calling subscriber with.

battery current for talking-purposes when the back-bridge relay 69 energizes, and also 1n conjunction withthe vertical line relay bridgerelay '39, comprising the windings 71 ;:and- 72, provides the called subscriber with talking battery current when the primarya,

- mechanism of the "connector shown in Figs.

circuit,of'the called substation is bridged across the line. The shaftwiper selecting 6 and 7 comprises a rotary magnet 56 and armature 73 adapted to engage the ratchet wheel/74.; wherebythe wipers (Fig. 8) may be. moved overthe contacts of the bank (Fig;

7 The-switching relay 59? is mounted upon Ta frameof-the switch, and when said magnet is in .an energized position the pawl 7 5 falls over the end of the spring 76,.locking the --relay in an energized position. Figs. 3, 4

and 5 show details, of the shaft and ratchet operating mechanism. It will be seen that the teeth 7 8 engaged by the vertical armature pawl are the-same as usual, while the usual rotary -teeth are replaced by the ratchet wheel 77 which is loosely mounted upon the shaft 78, ,so that the shaft may be raised and lowered without. moving the -wheeli77. However, when'the rotary -mag-.

net-operates, the rotary; armature pawl 7 9 engages the ratchet wheel and rotates the Y shaft" through the medium of the member I "79. It will be-seen that'the spring which mcupies the shaft slot and engages the teeth 55. "Figs. 10, 11 and 12 is shown the connector "bankarrangem'ent. In Fig. 12 the level M, Io iwhich'may be called the master level, 1886i? otfinto five groups of ten contacts. each, 'making, fifty in theleveL. Just above the 78*.Qwhe'h the shaft is rotated'is flexible. In

levelM (Figsill and 12) is'a row of groups goddehundreds line banks L,.each group comprising ten levels of ten contacts, making ve groups of one hundred line contacts each. Immediately above the line b'anks The back- L'are the privatebanks' P corresponding to the line banks L; -.Above the banks P are.

even-hundreds banks L and P (duplicates of the banks L and?) tions for another five. hundred lines, making a total-of one thousand line contacts in the whole bank (Fig. 12). The wipers 47 and 18 are adapted to. make contacts with the banks L, and the-wiper 49 with the banks P;

Mounted .upon the shaft 78 immediately above thisset of wipers 'is a second set 50,

51-and 52 (-Fig'..1)'- adapted to engagethe contacts of the'banks L and P The wiper- 80, whlch is adapted toengage the contacts ofthe master level M, is ri idly secured to the shaft -78, as'are the line and wipers, so that when the shaft is raised or with accommodaprivate lowered the wiper iscarriecl along. The.-

f function-of the master level M and the operation of thewiper selector switch (Figs. '1 and are as follows: The master level M n a way controls. the rotary magnet 55 contacts 84, 85,86, etc a, but, as shown in Fig.

1. this ground is, however, controlled by the wiper selector .switch. are permanently grounded at' G Among the functions of the wiper and. hundred 'or' group-selecting mechanism of the connector are the following: F irst, and as already indicated, to pick out'for the use of the connector eitherv one of the sets of main shaft wipers allottedto the connector, the 'set' beingdetermined by the'locat'ion. of the line desired. Ifthe line is in the series of banks L (Fig. 12), the wipers 47, t8'a'nd 19 will be selected, and if the line is in the series banks L the wipers 50, 51 and 52 will be selected.

' It becomes evidentthat the'arrangement of the banks in Fig. 12- is to obviate the necessity of providing means for rotating the shaft 78 through toogreat an are, or of'making the bank contacts too small, on the one hand, and on the other hand to limit the vertical movement {of'the shaft to ten steps.-

The next function 'of this connectorauxiliary mechanism is to rotate the shaft and its wipers. adjacent to the proper hundredgroup .of the bank contacts in the series of anks L and L (Fig. .12) before the imare sent in for carrying the wipers into actual contact with the line .desired. It 1s, therefore, apparent that these functions of p the connector auxiliary mechanismare performed by the first set-of impulses that are "transmitted to theconnector switch after The other contactspulses'correspondin'g to the last twodigits connection has. been established with said connector. This connector, unlike the ordinary connector, requires three dial opera-- tions to accomplish its full function. The first set of impulses thatare directed to the connector (in this case corresponding to the impulses of the second or hundreds digit) affect the connector switch and its auxiliary as follows: The impulses to the vertical line operate the vertical line relay 53, which in turn operates the rotary magnet 56 of the auxiliary mechanism. Normally the wipers 88, 89 and 90, 'orthe main wiper-selecting wipers, are out of engagement with the bank contacts to which the various sets of main switch wipers are multipled; and

normally the insulation on the terminal of the wiper 81 maintains. the first bank con tact 8% of .the main level hi insulated from ground G One verticalimpuise operates to carry the wipers 88, 89 and 90 into engagement with the main shaft wipers;47, 4:8 and 49, but it is insufiicient to rotate the insulating end of the wiper 81' away from the contact 82 to which the first bank; contact 84 is connected, nor into engagement with the contact 83. A second impulse over the vertical line willcarry the wipers 88, 89 and 90 intoen agement with the main shaft wipers 50, l and 52 of the evenhundreds, and will carry the insulation on the wiper 81 forward so as to insulate the contact 83 from ground G but still not enough to permit the contact 82 to fall into connection with the ground G. The next impulse to the vertical line'w ill move the wipers 88, 89 and 90 into engagement with the odd numbers main shaft wipers 47, 48 and 49, and then for the first time the insulation on the wiper 81 clears the contact 82, whereby the first contact 84: of the section a on the masterlevel M is grounded, with the result that the rotary magnet of the connec- 19, respectively, as shown in Fig. lg and' when operated two, four, six, eight or ten steps. the said wipers the shaft wipers 50, 51 A A clearer understanding of the object of this arrangemcm in my improved connector switch may be had from an explanation of its operation when one subscriber calls another. Suppose. for example, that the subscriber-at substation D Fig. 1) desires to signal the subscriber at substation D (Fig.

are connected with and respectively.

a the number of which is 2120. The dial at the calling substation is operated in the well-known manner forea'ch digit. When the dial is turned for the first digit the firstselector switch C is operated to select the connector switch .A, and the'grounding of the line conductors for the three remain ng 7 digits is effective in operating the connector switch. The ground impulses for the second digit operate the wiper selector device to pick out the proper main shaft wipers 47, 48, 49 or 50,51, 52, and also rotate the said main shaft wipers adjacent to the certain hundred-group determined by the second digit. For the last two digits the connector switch operates in the usual manner to select a certain line from said hundred-group.

The calling subscriber suitablyoperates the dial for the first digit 2. On the return motion of the dial the vertical-impulse spring 12 and the rotary impulse spring 14 come into contact with the groundpost 21 in the order named, grounding the vertical and rotary line conductors 91 and 92, respectively, the former twice and the latter once. After the firstdigit is called the first-selector shaft wipers 32, 33- and 34 are raised to the second level of the line andprivate banks as vfollows: When the spring 12 engages the ground post 21 an energizing circuit is established through the vertical relay 40 of the first-selector C. The current in this circuit flows from ground G through the springs 19 and 20 to the ground post 21, thence to the vertical impulse spring 12, vertical line conductor 91. side switch wiper 36, contact point 93, vertical line relay 40,

through the bridge-cut-ofi springs 94 and 95 to the battery lead 96, thence'through batte'ry B to ground G. Each time that the vertical line relay 40 is energized the springs 97 and 98 are pressed into engagement, and an energizing circuit is each time established through the verticalma'gnet 4:3. The circuit through the said magnet extends from ground G to the springs 98 and 97, private magnet springs 98 and, 99, vertical magnet 43 to the battery lead 96, thence through batteryB to ground G. The tertical magnet being operated twice, the ifi'rst-selector switch shaft wipers 32, 33 and 34 are carried opposite the first contact of the second bank 7 levelthat comprises the contact points which constitute the terminals of the trunk-lines leading to the connector A. Following the vertical impulses the rotary impulse spring becomes into contact with the groundv post 21, thereby grounding the rotary line conductor 92 once and energizing the rotary line relay 41 of the first-selector once. T he path of the energizing circuit nay be traced.

point 100, rotary line relay 41, bridge-cutolfsprings 101, 94 and 95. to the battery lead 96, thence through battery Bto, ground Gr. The'rotary line relay 41, upon-energizing, closes the springs 102 and 98 in contact, thereby closing an energizing circuit through the private 'magnet 35 which extends from ground G through the springs 98 and 102, private magnet 35 to'the' battery lead 96, -thence through battery B to ground G The private magnet 35 being energized springs 104, thence through the rotary magnet to the battery lead 96, andthrough bat-' .tery B'to gr dund G. The rotary magnet is energized once, and the shaftwipers 32, 33

and 34 are carried into engagementwith they bank contacts that constitute the terminals leading to the connector switch A,.-assumiiig that the trunk leading to the said connector I leads off from the first set of contacts of'the second level. But if the firsttrunk-line is busy, the first private bank contact is grounded in the well-known manner, and an energizing circuit is established through the. private magnet when the private wiper 34 strikes the grounded private bank 35 contact, thereby retaining the side switchim the energizing circuitthrough the rotary mag-.-

second position and thus maintaining net 44., The rotary magnet, by continuing to .rotate the wipers, breaks the energizing- 40 circuit of the private magnet as 'soonas an idle line is found, and as soon as the private magnet is denergized the side switch is tripped intothird position; but if there areno contacts to be passed over, assumed n the first instance, the rotary magnet 44, as is well known, trips the side switch to third p o-.

sition, with the resultthattheside switch wipers 36,37, 38 and 39 engage the contact points 105, 106, 107. and 108", respectively,

- thus extending the subscribers line conductors 9l-and 92 to the connector A.- Also,

since the side switchwiper 38'engages the grounded contact point 107, a guarding po- I tential is established at the private wiper 34- 155 -for-protecting the seized trunk-line from being molested by any other switch. The second digitis called after the subscriber has established connection with'the connectorA v p 118,}sw1tching relay59 to, the battery lead by way of the trunk-conductors 108 and 109.- p

9'6, thence-through battery B to gro'undLG. 125

00 The subscriber also rotates the'dia-l for the secondldigit 1, thereby grounding the 'verticalm-and rotary line'conductors 91 and 192, which causes theenergiz'ation .ofthe connector vertical and rotary line relays 53 and I 57. The-current .for energizingthevertical relay 53 flows over the following path:

from ground G through the vertical impulse spring 12, vertical line conductor 91,

side sw'itch, wiper 36, first-selector shaft wiper 32, conductor 108 to the vertical line relay 53, through the winding 67 of the differential relay 66 to the-battery-lead96, and

' through battery- B to ground G. Of course,

the relay 66 becomes energized, since the winding 67 is in series with the vertical line relay 55, but the energization of the said. difl'erential relay at this time is without. efi'ect. Each time that the'vertical relay 53 is energized the line relay springs 110 and 111 are pressed into contact, thereby 'closing an energizing circuit through the rotary magnet 56 of the wiper selector. This circuit extends from ground, G through the springs 111 and 110, conductor 112,.springs' .113 and 114, through the rotary magnet 56 to the battery lead 96, thence through bat-' tery'B to ground G. The vertical line relay [being energized once for the second digit,

the rotary magnet 56 is energized once and operatedtoattract its-armature 7 3, whereby '90 the ratchet wheel 74 and the wipers8l, 88,89

' and are moved one step. Normally these wipers rest in the position shown'in Fig. 7, but after operating one step the fiberwiper 81 still separates the'contact 82 from ground connection, and the wipers 88, -89'and .90

. engage the first bank contact which is connected th the shaft wipers 47, 48" and 49-,

which erare adapted to engage'the banks L an '1: Fig. 12) The wiper. 80 rests'on the contact 84, and the wipers 47 and 48 are opposite the first hundred-group of the bank vL, and the wiper. 49 isopposite the private bank P; also, the wipers 50, 51 and 52 0ccupy the same relative position with r'efer- 1'o5.

ence to the banks l andP hen the rotary impulse spring 14 is grounded at the substation, the rotary line relay 57' is ener-- gized by current fiowing'froin ground G.

through the ground springs 19 and 20, 4110 ground 'post- Q1,;impulse spring 14, rotary line conductor 92, side'swi-tch w per 37, contact point. 106, shaft wiper 33, conductor 109, rotary line relay 57, winding 68 of the] differential relay 66, back-bridge relay springs 11,5 and 116 'to the. battery lead 96, thence from battery Bto-ground G. The

rotary line relay, upon energizing, operates.

to place "the springs 117 andll'l'in contact,

thereby closing an energizin circuit through 1.20 the switching relay 59. .tends from-ground G through the springs his circuit ex- 111 and 117 switching relay'springs 76'and This relay, upon energizing, ,operates to shift the springs 76-and from engage: ment with-springs 118 and 114. into engagement with the. springs 119 and 120. -When/ the relay 59 thus energizes, the lockingpawl $30 v terminals of the ringer generator E across A signaling. current is, therefore, sent'from the generator 'Eto the ringer relay'springs. 135 and136, side switch wiper 60, contact point 137,

2), condenser139, ringer 140, springs-141' and 142.130 the rotary lineconductor 143, ro- 1'0 the. called subscribers line.

wiper 88 to the shaft wiper 47 normalconductor 124,- vertical line conductor 138 (Fig.

tary normalconductor 125, shaft wiper 48, wiper 89, contact point 144, side switch I wiper 61, ringer relayspr'ings 132 and 134 backto the generator; As soon asthe' calling subscriber ceases to press the signal ing button the ringer relay 70 becomes deenergized, and the springs 132 and 133 resume their normal position. The subscriber at substation #2120, in response to the signal, removes the )receiver 145 from the switch-hook 146, which allows the springs 147 and 148 to engage andthe springs 141 and 142 to disengage, therebyremoving the ringer 140 from across his line. The env, gagement of the springs 14:7 and 148 closes a series energizing circuit through both windings of the relay 69 at the connector A, said circuit extending from ground G to "the. contact point 127, side switch w per 62, winding 72 of the relay 69, through the the battery lead 96) to the spring 152, which ringer springs 132 and 133, side 'switclr wiper 61, contact point 144, wiper 89, shaft wiper 48, rotary line conductor 125, line'con-' ductor' 143,- thrOugh the primary winding 149, transmitter 150, through the springs 1,47 and 148, vertical line conductor 138, norma'l conductor 124,.sjhaft wiper 47, wiper 88,-

contact point 137 through the winding 71 of the relay 69, springs 151 and 131 to the battery lead-96, thence through battery B to ground G. The relay 69, upon energizetion, operates to shift the spring 115 from the spring 116 (which latter is connected to is 111 turn connected with ground. This reversal ofvthe polarity of the spring 115 sets up. an energizingcircuit which supplies the:

, calling subscriber with talking battery current; -ground G to the contact point 127, :slde "switch'wiper 62, through the sprlngs 152 The circuit may .be traced from and 115, winding 68 of the differential relay 66,'rotary line relay 57, shaft wiper 33,

' .side'switch wiper 37, rotary line conductor 92, primary winding 5, transmitter 7, springs .55

25. and'24 to the vertical line conductor 91, side. switch wiper 36, vertical llne relay 53,

winding 67 ofthe differential relay 66 to the battery lead 96, thence through battery -B-to -ground G. The two substations are now connected, and communication may be arried on over the circuit shown by heavy lines in Figs. 1 and 2. p

. The release of the switching apparatus'is bi ughtabout when the calling subscriber restores the receiver to the switch-'hoolr3,

and 31 into engagement for amoment- The contact of the said release springs grounds the vertical and rotary .line conductors 91 and 92 simultaneously from ground G to :the release spring 31, thence through the springs30 and 29 to the vertical and rotary line conductors. The grounding of the rotary line conductor 92 produces a shortcircuit of the rotary lin'e relay 57 in series with the winding68 of; the differential relay. 66 extending from ground G to the contact point 127, side vswitch wiper 62,.

springs 152' and 115, winding 68of the differential relay66, rotary line relay 57 to the rotary-line conductor '92, to the release springs 30 and 31 and to ground G. There- 'fo1e,since the winding 67 of the diiferential vrelay 66 alone carries current, the said relay now becomes energized and attracts its armature, which latter shifts the spring 131 from contact with the spring 151 into contact withthe spring 130. The disengageinent of the springs 131 and 151 destroys the energlzing circuit throughft-he relay 69, and

the spring 115 passes out of engagement thereby pressingthe release springs 29, '0

with the spring 152 and into contact with the spring 116, which removes the said short-circuit of the rotaryline relay 57 and winding 68, and establishes instead an energizing circuit extending from the substation ground G through the release" springs 31 and 3O to .the rotary line conductor 92, side switch wlper 37, shaft wiper 33, relay 57,

winding 68 of the dili'erential relay 66,- through the springs 115 and 116 to the battery lead 96, thence-through battery B to ground G. The rotary relay 57 now operates, and the springs 153 and 154 come into .contact, whereby an energizing circuit is established through the release relay 46 of the first-selector C in series with the release magnet 59 of. the connector A: However,

magnet '59, springs 130'and 131 to'the batf 'tery lead 96, and through battery B to ground G. -When the connector release magnet 59 is thus supplied with current it energiz'es, and as a result the switch ,shaft'and slde switch .are restored to normal position,

thus breaking the connection between the connector switch shaftwipers 47, 48 and 4:9

and the normal conductors 124, and-126. The back-release relay 46, being in the same circuit with. the release magnet, energizes simultaneously with the latter and operates tov close a circuit through the selector release magnet-45 by pressing the back-releasesprings156 and 155. together. The circuit through the said release magnet extends from ground through the springs and 156 to the release magnet 45, thence to the battery lead 96, and through battery to ground G. \Vhen the ground to the line conductors 91 and 92 is interrupted, all the magnets involved in the release are then deenergized, and all of the switches are fully restored. It will be understood, of course, that when the connector switchA is released and the wipers 47 and 4:8 disengage from the normal conductors 124 and 125, the backbridge relay 69 of the connector A is restored, and the spring 115 returns into normal engagement with the non-grounded battery spring 116, thus cutting off talking battery current from the calling line, and deenergizing the bridge cut oifrelay 128 of the selector C.

If the called line #2120 is busy at the time that the calling subscriber #5000 attempts to establish connection, the connector A is released by the last impulse to the rotary line conductor 92 as follows: The said impulse energizes the rotary line relay 57 of the connector A, which relay in turn energizes the. private magnet 58, pressing the private springs 157 and 158 into contact after the private wiper 49 has been carried onto the grounded private bank contact. It is understood, of course, that whenever a line is busy the connector private bank 157 to the release magnet 59, thence to battery B and to ground G. The connector switch. shaft and side switch are thus released in the well-known manner,'and connection is not established with the called line. The busy signal is, of course, established when the subscriber presses his sig naling button after: he has completed the calling operations and, of course, after the connector is released, as described, in which case the connector side switch is in first position, as explained. As a result the vertical line conductor 91 is grounded when the signaling button spring 26 is carried onto the ground contact 28, whereby the vertical line relay 53 is energized. Therefore, the line relay springs 110 and 111 are brought into contact, and the vertical magnet 54 is operated to raise the switch shaft, whereby the ofi'-normal springs 159 and 160 are brought into contact and a busy-signaling current sent to the calling substation 5on1 the busy coil F through the springs 169 and 159 to the side switch Wiper 61, ringer relay springs 133 and 132 to the calling sub scribers rotary line conductor 92, thence through the primary winding 5, transmitter he grounds the line conductors 91 and 92 simultaneously, energizing the line relays 53 and 57 of the connector A, as already explained, and producing the release of the switching apparatus as formerly. Furthermore, when the connector release magnet energizes, the wiper-selecting mechanism is also released. Referring to Fig. 3, it. will be seen that when the release 'armaturelGl is attracted by the release magnet 59, the

link 162 is drawn forward, and when thus moved (see Figs. 6 and 7 it rocks about the pivot point 163, and the finger 164 imparts an outward movement to the members 165 and 166. The locking link 75 then moves about the pivot point 167, freeing the springs 76' and 113. Also, when the pawl 165 is moved about its pivot point 168 the ratchet wheel '74 returns to normal position, owing to the tension of the coil spring 169. Thus when the calling subscriber restores his receiver to the switch-hook, all of the.

central station switching apparatus which he brought into use is fully released and returned to normal position.

In the foregoing it was shown how the connector switch was operated to select a particular subscribers line from the first hundred-group; It will now be pointed out how the connector operates to select any particular hundred-group from the ten groups in the connector bank. Assur a, forexample, that it is desired to select the line 25 1n the N-group (Fig; 12) which, in this case, occupies the position of the sixhundred-group. After the first-selector switch has extended connection'to the connector switch A the dial is turned for the digit 6. This energizes the vertical line relay 53 which in turn energizes the rotary magnet 56 of the wiper selector, whereby the wipers 81, SS, 89 and 90 are advanced six steps. In advancing six steps -the wiper S1 permits the contacts 82 and S3 to be grounded while the contacts 87 and 87 are disconnected from ground. In Fig. 1 it will be seen that when ground is provided to the contact 82 an energizing ductor 171, interrupter springs 172, rotary magnet 55 to the battery lead 96, thence 'through-batte'ry B to ground G. The rotary 'magnetthen operates to automatically rotate the shaft wipers. When the wiper cuit isostablished extending fromground GK When the wiper reaches the contact 85 it finds this'conta'ct also grounded, beoause at the auztiliary switch the spring 83 has beenperniitted to close circuit with ground G Therefore, the rotary magnet still does not stop, but passes the wiper 80 ontothe grounded section. b, and the connector con-.

' tinues to rotate until thewiper reaches the contact 86' which is'not'grounded, the contact STbeing separated by the insulation on nector in the thirty-one-hundredboard, and so on, as indicated. 'It is obvious that the subscribers of these eleven-hundred, twentythe wiper 81'froin' ground G As soon as the wiper 80 reaches the non-grounded con tact 86 the connector shaft is stopped. The

shaft wipers now occupy the position shown diagrammatically at 50, 51, ,52, 47, 4:8 and 49 in Fig. l2,'and when the dial isturned for the digits 2 and 5-bothsets of wipers are raised two steps and then rotated five steps into .contact with the terminals, of the line #25. The lower set of shaft wipers engage contacts of the banks 1 and L, while,

the upper set of shaft wipers. engage contacts in the banks P and L but it will be remembered that when the wiper selector I operated, the wipers 88, 89 and 90 were rotated to-the sixth contactto which are con nected the shaft, wipers 50, 5lland 52, thus extending the calling line conductors to the top set of wipers instead of to the lower set. Suppose that the line #25 of the live-hundred-group is desired; in that event the wiper selector is rotated five steps, and the gwipers 88, 89 and 90 are. connected with the lower set 47, 4'8 and 459. Both sets of wipers,

'.'however, will be connected with line 25 of their respective banks.-

From the forego ng it will be seen that my connector switch is adaptedto make connection with any one of a thousand lines, [as diagrammatically represented in Fig. 12.

' It is obvious that in a system like the one herein described all of the connector switches are not accessible to all of the subscribers. .This will become evident upon In this figure four being marked. At the left is shown the 'onethousand-division, and of this thousand division there are-shown four one-hundredgroups, namely the eleven-hundred-group.

the twelve-hundredgroup. the thirteen-him dred-group and 'thefourteen-hundredgroup. The two-.tliousand-division is shown to the right of the one-thousand-division,

and four of the one hundred-groups of this thousand are also shown. The same is true of the three-thousand and four-thousand divisions, which are shown in the order named to the right of the two-.thousand-division. In each hundred-group, asshown, there is contained a group of first-selectors and a group. of connectors; The number of-firstthat its wipers are raised to the first level, it

may .then be rotated in .this level and thus obtain .-connectionwith a connector inlthe eleven-hundredboard. From the second level'the same selector may obtain connection'with-a connector in the twenty-one-hun- 'dred-board. From the third level the firstselector may obtain connection with a conone-hundred, etc, boards have not .access to the connector switches in the various.thousands of a different hundred denomination, and t is, of course, obvious that it is not necessary that. theyshould. Since the connectors are of a one thousandcapacity, all

of the subscribers in the one-thousand-division have contacts in the banks of all of the connectors in their thousand division. With this arrangement all of the subscribers in the same thousand have accesst o all the con'- 'nectors inthe same thousand. It is also obvious that with this arrangement a two-hundred-subscriber of the first, thousand can reach any. subscriber in the two-thousand.

division, for example, by the use of a connector on the two-hundred-board of the twothousand division; He can. reach a subscriber in the three-thousand-division through a connector in the two hundred- .ioo

board of the three-thousand-division, and'so on. In other words,.all of the connectors in -the likehundreds of the various thousand sections are commonto all of the subscribers 7 of the like hundreds of saidthousands. This trunking arrangement is,.therefore, a

departure from: theusual method of trunk a i I I I From the foregoing it will be seen that I provide-a connector in which. terminate one thousand subscribers lines, notwithstanding the fact that said connector has but two sets of wipers, one for usein conjunction with subscribers lines having odd'hundred numhas, and the other for use in conjunction with subscribers lines having even numbers.

The selection of thewipers always takes place .in accordance with the second digit ofthe called number. The wiper selector will select one wiper and then the other and continue this operation until 'the proper selection has. been made, and thus the subscribers lines-can be numbered from 1 to 9999 in the ordinary manner. Vithout such arrangement for selecting the wipers it will be seen that the second digit of each subscribers number would necessarily have to be either one or two, and that this or any 5 other equivalent repetition in numbering the subscribers would interfere with the general scheme of numbering, and would result in a general disarrangement or radical modification of the system of trunking. lVith my improved arrangement, however, inv lving means for selecting one wiper and ftlre n the other, and then repeating this operation as many times as maybe necessary in order to call the second digit of the called number, it will be seen that subscribers are numbered in the usual and ordinary manner, the second digit of each number vary ing from 1 to 0, resulting in a uniform and consecutive numbering of the different subscribers. If the second digit of the called number is one, then the wiper selector gives the calling subscriber the first set of wipers, which latter operate in conjunction with the group of banks containing the terminals of all lines the numbers of which have odd numbers for their second digits. If. however, the second digit of the called number is 2, then the wiper selector passes fromthe first set .of wipers to the second set of wipers, which latter set operates in conjunction with the group of banks containing the terminals ofthe subscribers lines the numbers of which have even numbers for their second digits. Now suppose. as previously explained. that the second digit of the called number is 3, then the wiper selector goes from the first wiper to the second wiper, and then back to the first wiper, and thus the tablished method of calling is preserved, notwithstanding the fact, as stated, that the connector gives the calling subscriber a choice of only two line wipers. If the second digit of the called number should be 8, then the wiper selector will pass from the first wiper to the second wiper, and this round or cycle of operations will be repeated four times, whereby the wiper selector will finally give the calling subscriber the second wiper, which latter is allotted to the even digit numbers. As explained, this se lection of the required wiper is under the direct control of the calling subscriber, being inv response to the number of impulses arbitrarily transmitted by the calling subscriber in accordance with the value of the second digit of the called'number. and he automatic selection of the required bank of line terminals by the wiper then takes place afterward and immediately before the step up and step-around operation of the connector in accordance with the la st two digits of the called number Consequently, the entire operation of the connector is divided into four parts, first the selection of the a proper wiper in accordance with the second 'digit of the called number; second, the automatic selection-of the bank ofline terminals corresponding to the second digit of the called number; third, the stepping up ofv the wiper to the required level in the selected bank in accordance with the third digit dred and thousand. the connector employed will be on the board of both subscribers: but

if the called subscribers line terminates at the one-hundred-board of the two-thousanddivision.-then the connector employed will be on this board and not on the board of the calling subscriber; and, similarly. should a subscriber of the one-hundrod-group of the one-thousand-division call a subscriber in the one-hundredgroup of the three-thousand-division, then the connector employed will be on the board of the said called s'ubscriber. Suppose, however, that a subscriber of the.one-hundred-group of the onethousand-division calls a subscriber whose line terminates in the two-hundred-board of the two-thousand-division. In such case the calling subscriber gets a connector on the one-hundred-board of the two-thousanddivision. inasmuch as all of the subscribers lines of this division are multipled in the different groups and are thereby representedin any connector of the said division: consequently, for this purpose it is unnecessary that the calling subscriber should use a connector onthe board of the called subscriber. A calling subscriber, in other words. always gets a connector on a board of the hundred to which the calling subscriber helongsthat is to say. if the calling subscriber is a one-hundred subscriber. then whenever he calls the connector which he uses will invariably be upon one of the onehundred-board's, depending upon into which thousand-division he calls. The connector is always on the board of the called subscriber if the called subscriber and the calling subscriber belong tothe same hundred:

=but if not, then the connector which the calling subscriber gets is in the same thousand-division to which the called subscriber belongs, but on av board of the same hundred to which the calling subscriber belongs. This, it will be seen, is due to the fact that the subscribers. lines of any particular division are each'pro'iided with multiple terminals ineach of the hundred groups of'that nector thereo n'has a terminal of the called line Furthermore, and-owing to the fact that each connector contains the terminals ofyone thousand lines, it is not necessary that any one subscriber have access to more thanone hundred connectors, which con-, nectors are divided into ten sets, each ,set

bearing terminals of and representing the lines of" a difierent thousand subscribers.

For example, ifni'a one thousand-one-hundred-subs'criber calls'a subscriber oi his own thousand and hundred, he automatically obtaius connection with the; first idle one of ten connectors on his own board, anyone of which connectors will serve his purpose, be-

tire one thousand lines of that division. however, that he calls a subscriber cause th/ey all contain .multiples of the en- Suppos in th then, in that case, .he 1s given the first idle I one of ten connectors on the board of the in, v Yticular. thousand and hundred has access to on the same basis 2 as the-connectors -tha't,

group, except that in such .other Words, gthefiexchange contains one hundred concalled subscriber, any one of which connector contains multiples of all of the lines in this particular thousand division; and this yv ould also be true should he call a subscriber in the one-thousand-two-hundred case the connector would not be on the board scriber, but on the salneboa'rd as before. In the one-thousand-division of nec tors, divided into ten sets, each set for use in calling and, consequently,'asubscriberof any paronly' one hundred connectors in the entire exchange, which, however, for the reasons given, is suilicient to insure good service to all of the subscribers, the maximum number of calls at the same time havin been demonstrated' by experience to be in the long run .not over ten per' cent. of the entire number of subscribers.

invention also contemplates the provision of second-selectors between the firstselectors and case the second-selectors will be arranged is to say,'there will be. certain selectors that are accessible tosome subscribers but not 1 accessible to others, and vthe total number of second-selectors will be total number'of connectors, which would'be ten thousand for' a one hundred thousand system, the switches of the one-hundredtwo-thousand-one-hundred-group;

of the called sub-,

from a different hundred;

the connectors, and in such.

the same as the.

p connectors a ten minor divisions;- f 1 5--' .group connected to one one 01000 (naught one t ousand), etc., divisions, each consisti 1g often one-hundredboards, :asv above described. In this onehundred-thousand system, furthermore, the

banks of the first selectors of the 100-boards 1n the 11000, 21 0 up to 91000 and 01000 groups are multi led just-as inthe ten-thousand system the 100-boards in the 1000,2000, etc., groups are' multipled. Similarly the banks. of.the. firstselectors of the 200-boards p I on for the first selectors of the 300, 400," etc., first selector groups are multipled in thissame manner, and so on throughout the entire system. The trunk lines leading from. the ten levels of the first'selector banks are connected to-the second selectors on the ten-boards whose first selector banks are n1ultipled. For. instance, trunks from the first level of the -100-boa rds of the 11000, 21000 group's, etc., are connected to the second selectors of the 100 board ofthe 1l000-g'roup (the first thousand in the ,10000 st grand division). The trunks" e second level of these same first selecto reiconnected to the second seIectors bIFthe 100-board of the 21000- ,group. The trunks from the first level of etc., group boards. Likewise, the

' the first selector banks of the 200-boards of these same thousand-groups are connected ;to the second selectors on the 200 -board of the 11000-group, etc]. Thebanks of the second selectors of the 100-boards of the 11000,-

. 12000, 13000 groups, etc., (the groups of the tipled in the same manner. The banks of each group of these second selectors that are multipled as above are connected to the connector's on the same boards. For instance, the first level of the banks of the second selectors :on the IOO-boards'fof the 11000, 12000, groups, etc., (the 10000 orfirst grand division) are connected to the connectors on ank of'the 12000 up to 02000 inheabove-named 11000,

.120 the'100 board of theIIOOO-group; The

oncl level of-the' same selector banks is connected to the connectors on the 100-board of the 12000-group. In a similar manner the banksflof all the connectors belonging .to a

particular thousand-group are mult'i'pled and connected -to; ;th1e-'- subscribers lines of that example, the banks of the thousand.

the boards of the; 11000- groups.

' of connectors, but each thousand corresponding lines. The banks of all the connectors of the 12000-group are granted September 5, 1906, to A E. Keith,

which systemis very similar to the one described herein, with the exception that in said patent the connectors have a capacity of only one hundred lines, thus limiting the capacity of the system to ten-thousand lines.

My invention. also contemplates the pro; vision of line switches of the type described in the Western E Zectm'mian of Chicago, Illinois,of January 11,318 and 25, 1908, for preliminary trunking between the subscribers linesand the first-selectors, and with such arrangement the first-selectors could be equal in number to the connectors, and to the secend-selectors if the latter are used. As the introduction of line switches into the system in order to decrease the number of first-selectors, as well as the introduction of secondselectors into the system in order-to increase.

the capacity thereof, will be readily understood, no illustration of such arrangement is necessary.

f hat I claim as my invention is 1. In a telephone system, a plurality of subscribers lines divided into groups, a set the subscribers of any group have access only to the connectors allotted to such group for calling any subscriber. 1n the dlfierent .2. In a telephone system, a plurality of subscribers lines divided into groups, each group representing. a different hundred, a set of automatic connectors for each group, and means for automatically trunking calling subscribers lines into connection with idle connectors, said trunking means affording the subscribers of any group access only to theconnectors'allotted to such group.

3. In a telephone system, a plurality of subscribers lines, automatic connectors less in number than said lines, andautomatic trunking means whereby certain subscribers have. access to some of said connectors and certain other subscribers have access to other connectors, each' subscriber thereby having access to only a portion of the total number subscriber having access to a sufiicient portion of the total number of connectors to permit the calling of any subscriber in the exchange.

4. In a telephone system, a switch comprising a bank of line terminals, a plurality of line wipers therefor. means by which a calling subscriber selects one of said wipers, and means by which the calling subscriber rents,

then operates all of said wipers by a ver ical and then a rotary motion to cause the select ed wiper to engage the terminal of the called line, saidwiper in its rotary movement passing over a plurality of contacts.

5. In a telephone system, a bank of line terminals divided and sub-divided, a plurality of line wipers, means by which a calling subscriber selects a wiper and a division of the line terminals, means for at thesanie time selecting the desired sub-division, and

- means by which the calling subscriber then operates the. selected wiper to seize the called line in the selected sub-division.

6. In a telephone system, line terminals arranged in banks, a shaft mounted for vertical and rotary motion, a plurality of line wipers thereon, means by which a calling subscriber selects one of said wipers, and means by which the calling subscriber then operates said shaft vertically and then in a rotary manner to cause the selected wiper to engage the terminals of the called line. said wiper in its rotary movement passing over a plurality of contacts.

7. In a telephone system, subscribers line terminals arranged in divisions, each division divided into groups, a line wiper for each division, means for selecting the wiper 0f the division in which the called line is found, means for selecting the required group in the selected division, and means for then operating the said wipers'to cause the selected wiper to engagethe terminal of the called line, all subscribers whose numbers are odd in a certain-digit thereof having lines terminating in one division, and all subscribers whose numbers are even in the same certain digit thereof having lines terminating in the other division.

8. In a telephone system, subscribers lines terminating in a bank of line terminals, a line wiper providing a path for talking curmeans for causing said wiper to have rotary motion to approach the bank, means for causing said wiper to then have vertical motion to attain a certain desired level in said bank, and means for then effecting a further rotary motion of the said wiper to obtain connection with a terminal in the selected level.

9. In a telephone system, subscribers lines terminating in a plurality of banks of line terminals, a line wiper providing a path for talking currents, means for giving said wiper a rotary motion from one bank to the other in approaching the desired bank. means for then causing said wiper to move fromone plane to another in the selected bank, and means for then efiectingfurther rotary motion of said wiper to, obtain connection with a line in the selected bank.

10. In a telephone system, a shaft mount ed both endwise and rotary motion, a plurality of wipers on said shaft, means for selectingleither wiper a plurality of times if a certain. digit of-the called number has a valuejdf-ginore than two, line. terminals a1:

-"ran'ged,;1' n bank form, and means for opcutting. the selected wiper to engage the terminal of thecalled line.

., 115111. a telephone system, line'terminals arranged in groups,.a plurality of line wipmeans by which the electrical impulses digit of the called number for a certain automatically extends connectiont'o one ofnals, a line wiper providing a-path for talking currents, and instrumentalitics controlled by.the calling subscriber for causing said wiper to have rotary and then vertical and then rotary; motion in findingthe line terminal of the called subscriber.

13. In a telephone .system, a plurality of sets of wipers, means for selecting thesesets 'in succession,-and for repeating the opera- "tion, according to the number called, and

-means, D for operating said shaft, said selecting provided with guarding means for controlling said wipers,

14'. In a telephone system, subscribers lines, means for interconnecting any two lines, said means including impulse-trans mit-ting mechanism, a wiper serving 'as a.

for talking currents, a wiper-selecting path a shaft carrying the wiper, means means comprising a relay for shifting the impulses from the wiper-selecting means to, which mech-' the shaft-operating mechanism, anism comprises a vertical magnet, a rotary magnet and a private magnet, substantially as described. v

15. A telephone system comprising *a,

switch including a plurality of groups of contact banks, a bank-group-selecting means in said switch comprising a shaft and suitable wipers, means for providing a guarding: potential to prevent said selecting means from selecting the bank fgroup' thus potential.

16. In a telephone system, groups of contact banks, means for establishing guarding potential for said groups of contact banks, comprising amaster bank divided nto sections-,each section having first contacts, and the remaining contacts in each section being connected together and with guarding potential, means for also connecting or disconnecting said first contacts to or from guarding potential, whereby a bank-group or bank-groups may be protected by guarding potential, and whereby said selecting means will not stop at such sect on or sections, but will continue to advance or roof steps.

found. 17. In a contact bank, wiper-selecting means; adapttate until the first unguarded contact is switch, a plurality of groups of contacts, a plurality of wipers, a group-Se lectmg means comprising a master-switch ed to rotate oversaid'wipers and comprising 1 the auxiliaryarrangement adaptedto establish a guarding potential for; a group of.-

.contact banks by grounding, the first con t'act'of that group each time that the wiperselecting means has completed one round of the wipers ancl'begun another.-

18. In a switch, a plural ty of groups of contact banks, 'bank-group-selecting means comprising Wipers 'foreachgroup, said bank-groups divided into even-number sections and odd-number sections, some of said wipers allotted to the even sections, some to the odd sections, means for selecting the wipers of either section, and means for applying guarding potential for determining which group of banks shall be selected. 19. In a telephone system, wipers, wiperselecting mechanism,-contact banks arranged in groups, grouprselecting'mechanism, line relays for controlling the group-selecting and the w per-selecting mechanism, and

means for transmitting current to control said mechanism, as set forth.

20. In atelephone system, a switch comprising a' bank of line terminals, a plurality of line wipers therefor, means by which a calling subscriber selects one of said wipers,

and. means by which the calling subscriber I then operates. all of said wipers by a vertical and' then a rotary. motion to cause the se- 7 lect ed wiper to engagesthe terminal of the" called line, there being more groups of lines than there are wipers. a c a 21. In a telephone system,- line terminals arranged in banks,

engage'the terminals of the called line, there being more groups of'line'sthan there are wipers.

a shaft mounted for vero tical and rotary motion, a plurality of line 22. In a telephone system, a connector switch, a plurality of lines terminating in terminals at said switch, said lines divided into a plurality of two-digit groups, a set of wipers associated with all of said lines, and means in said switch for moving said wipersadjacent to any one of said groups and for then moving said wipers-into engagement with any terminal in the adjacent group in response to a two-digit operationin the number of said terminal, each operation of the wipers to moefrom any group to an adjacent group requlring a plurality 

